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Tidy up ElfReader

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This commit is contained in:
Katy Coe
2019-10-21 00:12:51 +02:00
parent bebfba4f46
commit 982b4b168d
1 changed files with 31 additions and 53 deletions
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72
Il2CppInspector/FileFormatReaders/ElfReader.cs
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@@ -7,17 +7,16 @@
using System; using System;
using System.Collections.Generic; using System.Collections.Generic;
using System.Diagnostics;
using System.IO; using System.IO;
using System.Linq; using System.Linq;
using System.Net.Sockets;
namespace Il2CppInspector namespace Il2CppInspector
{ {
internal class ElfReader : FileFormatReader<ElfReader> internal class ElfReader : FileFormatReader<ElfReader>
{ {
private program_header_table[] program_table_element; private program_header_table[] program_header_table;
private elf_32_shdr[] section_header_table; private elf_32_shdr[] section_header_table;
private elf_32_dynamic[] dynamic_table;
private elf_header elf_header; private elf_header elf_header;
public ElfReader(Stream stream) : base(stream) { } public ElfReader(Stream stream) : base(stream) { }
@@ -47,8 +46,19 @@ namespace Il2CppInspector
// 64-bit not supported // 64-bit not supported
return false; return false;
} }
program_table_element = ReadArray<program_header_table>(elf_header.e_phoff, elf_header.e_phnum);
program_header_table = ReadArray<program_header_table>(elf_header.e_phoff, elf_header.e_phnum);
section_header_table = ReadArray<elf_32_shdr>(elf_header.e_shoff, elf_header.e_shnum); section_header_table = ReadArray<elf_32_shdr>(elf_header.e_shoff, elf_header.e_shnum);
if (program_header_table.FirstOrDefault(x => x.p_type == 2) is program_header_table PT_DYNAMIC) // PT_DYNAMIC = 2
dynamic_table = ReadArray<elf_32_dynamic>(PT_DYNAMIC.p_offset, (int) PT_DYNAMIC.p_filesz / 8 /* sizeof(elf_32_dynamic) */);
// Get global offset table
var _GLOBAL_OFFSET_TABLE_ = dynamic_table.First(x => x.d_tag == 3).d_un; // DT_PLTGOT
if (_GLOBAL_OFFSET_TABLE_ == 0)
throw new InvalidOperationException("Unable to get GLOBAL_OFFSET_TABLE from PT_DYNAMIC");
GlobalOffset = _GLOBAL_OFFSET_TABLE_;
return true; return true;
} }
@@ -61,26 +71,22 @@ namespace Il2CppInspector
if (SHT_STRTAB != null) { if (SHT_STRTAB != null) {
// Section header shared object symbol table (.symtab) // Section header shared object symbol table (.symtab)
if (section_header_table.FirstOrDefault(x => x.sh_type == 2u) is elf_32_shdr SHT_SYMTAB) // SHT_SYMTAB = 2 if (section_header_table.FirstOrDefault(x => x.sh_type == 2) is elf_32_shdr SHT_SYMTAB) // SHT_SYMTAB = 2
pTables.Add((SHT_SYMTAB.sh_offset, SHT_SYMTAB.sh_size / SHT_SYMTAB.sh_entsize, SHT_STRTAB.sh_offset)); pTables.Add((SHT_SYMTAB.sh_offset, SHT_SYMTAB.sh_size / SHT_SYMTAB.sh_entsize, SHT_STRTAB.sh_offset));
// Section header executable symbol table (.dynsym) // Section header executable symbol table (.dynsym)
if (section_header_table.FirstOrDefault(x => x.sh_type == 11u) is elf_32_shdr SHT_DYNSYM) // SHT_DYNSUM = 11 if (section_header_table.FirstOrDefault(x => x.sh_type == 11) is elf_32_shdr SHT_DYNSYM) // SHT_DYNSUM = 11
pTables.Add((SHT_DYNSYM.sh_offset, SHT_DYNSYM.sh_size / SHT_DYNSYM.sh_entsize, SHT_STRTAB.sh_offset)); pTables.Add((SHT_DYNSYM.sh_offset, SHT_DYNSYM.sh_size / SHT_DYNSYM.sh_entsize, SHT_STRTAB.sh_offset));
} }
// Symbol table in dynamic section (DT_SYMTAB) // Symbol table in dynamic section (DT_SYMTAB)
// Normally the same as .dynsym except that .dynsym may be removed in stripped binaries // Normally the same as .dynsym except that .dynsym may be removed in stripped binaries
if (program_table_element.FirstOrDefault(x => x.p_type == 2u) is program_header_table PT_DYNAMIC) // PT_DYNAMIC = 2
{
// Get the dynamic table
var dynamic_table = ReadArray<elf_32_dynamic>(PT_DYNAMIC.p_offset, (int) PT_DYNAMIC.p_filesz / 8 /* sizeof(elf_32_dynamic) */);
// Dynamic string table // Dynamic string table
var DT_STRTAB = dynamic_table.FirstOrDefault(x => x.d_tag == 5u); // DT_STRTAB = 5 var DT_STRTAB = dynamic_table?.FirstOrDefault(x => x.d_tag == 5); // DT_STRTAB = 5
if (DT_STRTAB != null) { if (DT_STRTAB != null) {
if (dynamic_table.FirstOrDefault(x => x.d_tag == 6u) is elf_32_dynamic DT_SYMTAB) { // DT_SYMTAB = 6 if (dynamic_table.FirstOrDefault(x => x.d_tag == 6) is elf_32_dynamic DT_SYMTAB) { // DT_SYMTAB = 6
// Find the next pointer in the dynamic table to calculate the length of the symbol table // Find the next pointer in the dynamic table to calculate the length of the symbol table
var end = (from x in dynamic_table where x.d_un > DT_SYMTAB.d_un orderby x.d_un select x).First().d_un; var end = (from x in dynamic_table where x.d_un > DT_SYMTAB.d_un orderby x.d_un select x).First().d_un;
@@ -88,7 +94,6 @@ namespace Il2CppInspector
pTables.Add((DT_SYMTAB.d_un, (end - DT_SYMTAB.d_un) / 16 /* sizeof(elf_32_sym) */, DT_STRTAB.d_un)); pTables.Add((DT_SYMTAB.d_un, (end - DT_SYMTAB.d_un) / 16 /* sizeof(elf_32_sym) */, DT_STRTAB.d_un));
} }
} }
}
// Now iterate through all of the symbol and string tables we found to build a full list // Now iterate through all of the symbol and string tables we found to build a full list
var symbolTable = new Dictionary<string, uint>(); var symbolTable = new Dictionary<string, uint>();
@@ -108,40 +113,13 @@ namespace Il2CppInspector
} }
public override uint[] GetFunctionTable() { public override uint[] GetFunctionTable() {
// Find dynamic section // INIT_ARRAY contains a list of pointers to initialization functions (not all functions in the binary)
var dynamic = new elf_32_shdr(); // INIT_ARRAYSZ contains the size of INIT_ARRAY
var PT_DYNAMIC = program_table_element.First(x => x.p_type == 2u);
dynamic.sh_offset = PT_DYNAMIC.p_offset;
dynamic.sh_size = PT_DYNAMIC.p_filesz;
// We need GOT, INIT_ARRAY and INIT_ARRAYSZ var init = MapVATR(dynamic_table.First(x => x.d_tag == 25).d_un); // DT_INIT_ARRAY
uint _GLOBAL_OFFSET_TABLE_ = 0; var size = dynamic_table.First(x => x.d_tag == 27).d_un; // DT_INIT_ARRAYSZ
var init_array = new elf_32_shdr();
Position = dynamic.sh_offset; return ReadArray<uint>(init, (int) size / 4);
var dynamicend = dynamic.sh_offset + dynamic.sh_size;
while (Position < dynamicend) {
var tag = ReadInt32();
if (tag == 3) //DT_PLTGOT
{
_GLOBAL_OFFSET_TABLE_ = ReadUInt32();
continue;
}
else if (tag == 25) //DT_INIT_ARRAY
{
init_array.sh_offset = MapVATR(ReadUInt32());
continue;
}
else if (tag == 27) //DT_INIT_ARRAYSZ
{
init_array.sh_size = ReadUInt32();
continue;
}
Position += 4;
}
if (_GLOBAL_OFFSET_TABLE_ == 0)
throw new InvalidOperationException("Unable to get GLOBAL_OFFSET_TABLE from PT_DYNAMIC");
GlobalOffset = _GLOBAL_OFFSET_TABLE_;
return ReadArray<uint>(init_array.sh_offset, (int) init_array.sh_size / 4);
} }
// Map a virtual address to an offset into the image file. Throws an exception if the virtual address is not mapped into the file. // Map a virtual address to an offset into the image file. Throws an exception if the virtual address is not mapped into the file.
@@ -149,7 +127,7 @@ namespace Il2CppInspector
// an exception will be thrown. This area of memory is assumed to contain all zeroes. // an exception will be thrown. This area of memory is assumed to contain all zeroes.
public override uint MapVATR(uint uiAddr) public override uint MapVATR(uint uiAddr)
{ {
var program_header_table = program_table_element.First(x => uiAddr >= x.p_vaddr && uiAddr <= (x.p_vaddr + x.p_filesz)); var program_header_table = this.program_header_table.First(x => uiAddr >= x.p_vaddr && uiAddr <= (x.p_vaddr + x.p_filesz));
return uiAddr - (program_header_table.p_vaddr - program_header_table.p_offset); return uiAddr - (program_header_table.p_vaddr - program_header_table.p_offset);
} }
} }